Would it be possible in the standard model to have atom like systems in which muons (or tauons) take the place of electrons? Why don't we see more of them? For instance it could be related to some mechanism leptogenesys, but I don't know much about this subject..
How the difference between muonic and electronic atoms could affect astronomical data?
Correct me if I am wrong, but I guess there is no analogue for protons and neutrons, especially since protons have very long life.